Cortical evoked potential monitoring. A system for intraoperative monitoring of spinal cord function.

This report describes the intraoperative use of a somatosensory cortical evoked potential system to monitor spinal cord function during 300 orthopedic surgical procedures. This system requires sophisticated equipment and the establishment of normative data but has performed well with no false negatives noted. The most frequent technical problem encountered was the effect of medications and anesthetic agents, some of which impair the evoked response significantly. In this series of 300 cases, three neurologic deficits were documented intraoperatively and confirmed postoperatively. There were four cases in which changes in evoked potentials led to change in operative procedure, with no subsequent neurologic deficit. In the remaining cases, the monitoring indicated no neurologic problems during surgery, and none were noted postoperatively.